Longest rivers of the United Kingdom

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The Severn Bridges crossing near the mouth of the River Severn
The River Thames in London
The River Tay in Perth, by measured flow the largest in Great Britain

This is a list of the longest rivers of the United Kingdom.

Longest rivers of the United Kingdom[edit]

Rank River Length (miles) Length (km) Mean Flow (m3/s)[1] Mouth Country
1 River Severn[2] 220 354 107.4 Severn Estuary Wales/England
2 River Thames[2] 215 346 65.4 Thames Estuary England
3 River Trent[2] 185 297 89.0 The Humber England
4 River Wye[3] 155 250 73.1 Severn Estuary Wales/England
5 River Great Ouse[2] 143 230 15.6 The Wash England
6 River Ure/River Ouse, Yorkshire 129 208 69.8 The Humber England
7 River Tay[2] 117 188 179.0 Firth of Tay Scotland
8 River Clyde 109 176 48.5 Firth of Clyde Scotland
9 River Spey 107 172 65.7 Moray Firth Scotland
10 River Nene[2] 100 161 9.3 The Wash England
11 River Bann / Lough Neagh 99 159 92.2 Atlantic Ocean Northern Ireland
12 River Tweed[2] 96 155 81.7 North Sea Scotland/England
13 River Avon, Warwickshire 96 154 17.3 River Severn* England
14 River Eden, Cumbria 90 145 53.7 Solway Firth England
15 River Dee, Aberdeenshire 87 140 47.8 North Sea Scotland
16 River Witham 82 132 5.2 The Wash England
17 River Teme 81 130 18.2 River Severn* Wales/England
18= River Don, Aberdeenshire[2] 80 129 21.3 North Sea Scotland
18= River Foyle 80 129 58.8 Atlantic Ocean Northern Ireland/Republic of Ireland
20 River Usk[4] 78 125 28.6 Severn Estuary Wales
21 River Teifi[5] 76 122 29.5 Cardigan Bay Wales
22= River Tywi 75 121 39.9 Carmarthen Bay Wales
22= River Ribble 75 120 34.0 Irish Sea England
22= River Avon, Bristol 75 120 22.2 Mouth of the Severn England
25= River Tyne[2] 73 118 45.2 North Sea England
25= River Swale 73 118 20.2 River Ure England
27 River Derwent, Yorkshire 72 115 17.4 River Ouse, Yorkshire England
28= River Aire 71 114 36.5 River Ouse, Yorkshire England
28= River Nith 71 114 36.5 Solway Firth Scotland
30= River Tees 70 113 22.2 North Sea England
30= River Medway 70 113 11.7 Thames Estuary England
30= River Mersey 70 113 37.1 Irish Sea England
33= River Dee, Wales[2] 70 112 34.1 Dee Estuary Wales/England
33= River Don, South Yorkshire 70 112 16.3 River Ouse, Yorkshire England

There seems to be little consensus in published sources as to the lengths of rivers, nor much agreement as to what constitutes a river. Thus the River Ure and River Ouse can be counted as one river system or as two rivers. If it is counted as one, the River Aire/ River Ouse/Humber system would come fourth in the list, with a combined length of 161 miles (259 km); and the River Trent/Humber system would top the list with their combined length of 222 miles (357 km).[6] Also, the Thames tributary, the River Churn, sourced at Seven Springs, adds 14 miles (23 km) to the length of the Thames (from its traditional source at Thames Head). The Churn/Thames' length at 229 miles (369 km) is therefore greater than the Severn's length of 220 miles (354 km). Thus, the combined Churn/Thames river would top the list. Sue Owen et al., in their book on rivers, generally restrict the length to the parts that bear the same name. Thus the River Nene is quoted at 100 miles (160 km), but would be around 5 miles (8 km) more if the variously named sources were included. Many of the above lengths are considerably different from Sue Owen's list, some longer and some shorter.[2]

Where a river ends in an estuary the conventional British approach has been to treat the river as ending at the end of the administrative zone. Thus the Severn ends at the mouth of the Bristol Avon and the Thames at the Yantlet Line. The currently accepted end of the Severn Estuary is about 18.5 miles (29.8 km) further, and the Port of London's authority stretches now to Margate, 30 miles (48 km) further. Other countries have different conventions, making comparisons of limited value. Those rivers which empty into other (non-tidal sections of) rivers are indicated in the table thus*. In Yorkshire, the Aire, Derwent and Don all empty into a tidal section of the Yorkshire Ouse.

The figures for mean flow are derived from those offered up by the National River Flow Archive, in particular the flow measured at the lowermost gauging stations on each named watercourse. Sometimes the figures of further downstream tributaries are combined with those of the main stem river to provide a more realistic flow figure for the lowermost non-tidal stretch of a watercourse. Some major UK rivers (in terms of flow) are omitted from the list above simply because they are also short.

See also[edit]


  1. ^ "Search Data". National River Flow Archive.
  2. ^ a b c d e f g h i j k Owen, Susan; et al. (2005). Rivers and the British Landscape. Carnegie. ISBN 978-1-85936-120-7.
  3. ^ "SSSI Citation River Wye (upper Wye)" (PDF). Natural Resources Wales. Retrieved 14 November 2020.
  4. ^ "Usk management catchment Summary" (PDF). Natural Resources Wales. Retrieved 14 November 2020.
  5. ^ - River Teifi - CCW Archived 2014-02-21 at the Wayback Machine
  6. ^ http://copranet.projects.eucc-d.de/files/000165_EUROSION_Humber_Estuary.pdf[bare URL PDF]